The present invention relates to a flashing device used in a camera, etc., and more specifically, relates to a flashing device in which stored energy for next light emission is not lost wastefully.
FIG. 1 is a circuit diagram showing the basic constitution of a typical flashing device which is used in a camera, etc.
In this figure, when a battery switch (strobo switch) 12 is closed, a current from a battery (secondary battery) 10 is provided through the battery switch 12 to a voltage-raising circuit 14. A high voltage appearing at an output of the voltage-raising circuit, which is about 300 V, is used to charge a condenser 16 and also applied to electrodes of a light-emitting tube 18. A discharge tube in which xenon gas, etc. is sealed, is employed as the light-emitting tube 18.
Furthermore, an emission control circuit 20 is provided in the above flashing device. When a trigger switch 22, which is linked with a release button, etc. of a camera, is turned on, a pulse signal is provided from the emission control circuit to a trigger electrode 18a of the light-emitting tube 18.
The flashing device is placed in its waiting state by having turned on the battery switch 12 prior to its actual use. When the light-emitting tube 18 is triggered, in this waiting state, by the trigger pulse signal which is produced in response to the turning-on of the trigger switch 22, it emits light for a short moment. This light emission is performed by using energy previously stored in the condenser 16. After the light emission the condenser 16 is charged again.
In this case, since the condenser 16 is automatically recharged, the electric charge remains when, after completion of use of the flashing device, the battery switch 12 is turned off. This remaining energy in the condenser 16 is lost (discharged) with a lapse of time and it scarcely contributes to the following light emission. This means a waste of energy, that is, a waste of the energy originally stored in the battery.